EP1416057A1 - Chrome free waterproof leather - Google Patents

Abstract

Chromium-free leather has a water-proofness measured as DIN 53338 penetration time of at least30 minutes. Independent claims are also included for the use of silicones as hydrophobicizers for chromium-free tanned leather; and production of the leather by treating with a hydrophobicizer, optionally after post-tanning.

Description

The invention relates to chrome-free leather with high water resistance, a method for its manufacture, its use as well as the use of silicones as Hydrophobing agent for chrome-free tanned leather.

There is an increased need for waterproof leather for shoes on the market, Clothes or bags. Now leather is inherently hydrophilic and most tanning and Retanning agents and fatliquoring agents are used by means of dispersing agents.

The usual waterproofing agents are non-sulfonated fatliquors as well Hydrophobic boosters that are fixed with mineral salts - usually with Chromium (III). Such systems lead to an open hydrophobization on chrome tanned Leather that is suitable for most applications being under open Hydrophobization, understood the generation of a hydrophobic network around the fibers without filling up the free spaces.

Applied to chrome-free leather, the desired water resistance can already be therefore cannot be achieved because the appropriate amount of chrome tanning agent replaced by large amounts of hydrophilic vegetable tannins and / or syntans must become. However, hydrophilic ingredients in leather favor penetration from water to leather and not the opposite effect of water repellency.

State of the art is, for example, H. Birkhofer, Reactive Hydrophobiermittel, Das Leder 1992, 71-75; Danisch, P. et al. Modem Hydrophobic Systems, JALCA, 1996, 120-125; Reiners, J. et al. Waterproofing of Leather, ALCA-Congress, Skytop, PA, 2002 (to be published JALCA 2002).

Therefore, due to their particularly outstanding properties, most are today used leather tanned chrome. Just some special leather like sole leather, Belt leather or leather for automotive fittings show up for your requirements even better properties if with vegetable and / or with instead of with chrome Syntan tannins were tanned.

However, the disadvantage of chrome-tanned leather is complex. For example Leather waste generated during the manufacture of leather articles and leather at the end of its useful life in terms of waste disposal problematic, especially since chrome is no longer stored in certain landfills may. In addition, chrome-tanned leather may have traces of Cr (VI) under certain Develop storage conditions or during combustion.

Alternative tanning systems that are on the market, such as aluminum, Aside from, glutardialdehyde or tetrahydroxymethylphopsphonium salt have ecological problems in themselves, the disadvantage that in all these tanning systems the Absence of chrome tanning salts usually through higher amounts of others hydrophilic tannins such as vegetable extracts and synthetic, aromatic syntans is compensated, with which the aforementioned incompatibility with the property the water resistance is problematic.

In addition, such substances increase the hydrophilicity of the leather and make it harder. In order to counteract this tendency again, larger amounts of Fatliquors are used, which in turn are applied with emulsifiers must, and in this way the water resistance is counteracted.

Chrome is tanned in the usual manufacturing process for waterproof leathers Leather with a combination of greasing agents and water repellents, in usually treated with silicone emulsions. Since this treatment is done in water the use of emulsifiers for the water repellent enhancers is also required, which in turn adversely affect water resistance. To the disadvantages of Avoiding hydrophilicity induced by emulsifiers is used in conventional, chrome-tanned systems, the emulsification is carried out by means of compounds, their emulsifying, functional groups destroyed in a subsequent fixing step can be. This is usually done with chromium salts.

The object of the invention was therefore to provide waterproof, chrome-free tanned leather.

The invention relates to chrome-free leather with a water resistance measured as Penetration time according to DIN 53 338 of at least 30 min., Preferably of greater than 2 hours.

"Chromium-free" in the sense of the present invention means not with chromium salts tanned. The maximum amount of chromium, e.g. caused by natural Sources of Cr content in animal skins or chromium-containing dyes in leather less than 2000 ppm.

For leather not dyed with chrome dye, the maximum proportion is Chromium in leather is preferably less than 100 ppm.

The chrome-free leather according to the invention preferably has a shrinking temperature greater than 70 ° C, especially greater than 75 ° C.

The leather according to the invention is preferred which has an iron content of 1 to 7% by weight. The iron content is determined as follows: A sample of the leather is to maintain the reference weight at 70 ° C in a vacuum to constant weight dried. It is then incinerated at 800 ° C, the Fe (III) content with a commercially available method determined by wet chemistry, and on the reference weight recalculated.

The iron content preferably results from tanning with iron salts.

Iron tanning is known in principle, see, for example, prior art Stather, Geranium chemistry and technology, Akademie Verlag, Berlin, 1957, 474-480; Heidemann E. at al., Possibilities and Limits of Iron Tanning, Das Leder, 1990, 8-14; Balasubramanian S. et al., Iron Complexes as Tanning Agents, JALCA, 12997, 218-224.

In a further preferred embodiment, the leather according to the invention has an Si content of at least 0.2% by weight, in particular at least 1.0% by weight determined as silicate after combustion.

The leather according to the invention preferably contains silicones as water repellents, especially those used in the description of the manufacturing process below were used as water repellents.

In a likewise preferred embodiment, the leather according to the invention has a water vapor permeability, measured according to DIN 53333, of greater than 0.8 mg / cm ² h, in particular greater than 2 mg / cm ² h.

Leather with a low water or steam content is extremely comfortable to wear. Therefore, the leather according to the invention is preferably by water absorption from less than 30 wt%, especially less than 20 wt% to Water penetration during the measurement according to DIN 53 338 or after 8 hours Marked water contact.

The invention further relates to a method for producing the invention Leather, which is characterized by the fact that one chrome-tanned Leather treated with a water repellent.

It is preferred to use a hydrophobizing agent which a) is self-emulsifying Is water and has ionic pH-sensitive groups and / or b) that in Combination with an emulsifier is used, the emulsifier being ionic has pH-sensitive groups.

Under pH-sensitive, functional groups are to be understood which a pH of 4.1 - 8 typical for retanning an emulsifying Have an effect sufficient to achieve a stable with the hydrophobic active ingredient to form aqueous emulsion, and by changing the pH, preferred Reduction to 2.5 - 4.0, especially 3.3 - 3.9, lose this emulsifying effect.

Preferred ionic, pH-sensitive groups are within the scope of this application for example carboxylic acids and / or their salts or amines and / or their Salts, substituted sulfonylureas or cyanureas and / or their salts understand. That Reaction products from toluenesulfonyl isocyanate and amines or Cyanamide and isocyanates, and their salts, which are added when base is added (triethylamine, NaOH) form.

Suitable lubricants for water repellency are those that are free of electrolyte-stable anionic emulsifiers, e.g. sulfonated, sulfated or sulfited compounds with an emulsifying effect. Come into question here e.g. Fats and oils based on long-chain alkanes, alcohols, esters or other hydrophobic hydrocarbons. These connections can be more natural or be of synthetic origin, such as, for example, fish oils, claw oils, vegetable oils or mineral oils.

In a preferred application form, these fatliquoring agents can be emulsifiers based on carboxylic acids, polycarboxylic acids or polyethers, to facilitate processing in an aqueous liquor.

The preferred hydrophobizing agents with ionic, pH-sensitive groups are to name appropriately modified silicones, especially polysiloxanes.

Suitable polysiloxanes are, for example, linear, branched or cyclic Polysiloxanes, which are optionally substituted. Polydimethylpolysiloxanes are preferred, which are optionally substituted. Suitable substituents are either via a spacer, optionally via heteroatoms or functional groups may be interrupted, connected to the main polysiloxane chain, or may also be bonded directly to a silicon atom of the polysiloxane main chain.

R

für einen C₁ bis C₁₂-Alkylrest, einen C₁ bis C₁₂-Alkoxylrest, einen Hydroxylrest oder einen Phenylrest steht,

a

für 0 oder 1 steht,

k

für 0 bis 50 steht,

c

für 1 oder 2 steht, und

n

für 10 bis 1000 steht,

A

für Wasserstoff, einen Alkyl-, Alkoxy-, Hydroxy-, Perfluoralkyl- oder einen Phenylrest, oder einen Rest der Formel R⁷-G-,

in der

R⁷

für Wasserstoff, eine Hydroxy-, Carboxyl-, Epoxy- oder Aldehydgruppe, (C₁-C₄)-Alkyl, (C₁-C₄)-Alkoxy steht
und

G

für einen zweiwertigen, gegebenenfalls verzweigten, C₂- bis C₆₀-Kohlenwasserstoffrest steht, der durch nicht benachbarte Ether-, Ester-, Amid-, Carbonat- oder Urethangruppen unterbrochen sein kann und der gegebenenfalls durch Hydroxylgruppen oder Alkyl- oder Arylreste substituiert ist, steht

oder A für einen Rest der Formel

steht, in der

R¹, R² und R³

unabhängig voneinander für Wasserstoff oder für einen einwertigen C₂-C₆₀-Kohlenwasserstoffrest stehen, der gegebenenfalls eine oder mehrere nicht benachbarte Ether-, Imino-, Amid-, Harnstoff-, Urethan-, Ester- oder Carboxylgruppen enthält und der gegebenenfalls mit einer oder 2 Carboxylgruppen -COOM und/oder 1 oder 2 Hydroxylgruppen substituiert ist,

wobei

M

für Wasserstoff oder Na⁺, K⁺, Li⁺, NH₄ ⁺,

steht,
wobei R⁴, R⁵ und R⁶ unabhängig voneinander für C₁-C₁₈-Alkyl, insbesondere C₁-C₄-Alkyl oder substituiertes C₁-C₁₈-Alkyl, insbesondere Hydroxyalkyl, oder Aralkyl, insbesondere Benzyl, stehen,
und wobei R¹ bis R³ unabhängig voneinander über eine Einfachbindung, eine Gruppe -COO-, -CO- oder -CONH- mit dem Stickstoffatom verknüpft sind, und
wobei R¹ und R² nicht gleichzeitig über eine Carbonylgruppe mit dem Stickstoffatom verknüpft sind,

D und E

unabhängig voneinander für einen zweiwertigen C₂-C₂₀-Kohlenwasserstoffrest stehen, der durch Hydroxyl substituiert oder durch nicht benachbarte O-Atome unterbrochen sein kann,

q

für 0 bis 3 steht,

mit der Maßgabe, dass mindestens eine Endgruppe der Formel (3a) vorhanden ist für den Fall, dass die Polysiloxankette nur Struktureinheiten der Formel (2) enthält.

Polysiloxanes are particularly preferred, characterized in that the polysiloxane chain has at least one structural unit of the formula (1) [AR _a SiO _{(3-a) / 2} ] _k and / or at least one structural unit of the formula (2) [R _c SiO _{(4-c) / 2} ] _n and optionally one or more end groups selected from the formulas R ₃ SiO _1/2 and AR ₂ SiO _1/2 contains, where

R

represents a C ₁ to C ₁₂ alkyl radical, a C ₁ to C ₁₂ alkoxyl radical, a hydroxyl radical or a phenyl radical,

a

represents 0 or 1,

k

represents 0 to 50,

c

represents 1 or 2, and

n

stands for 10 to 1000,

A

for hydrogen, an alkyl, alkoxy, hydroxy, perfluoroalkyl or a phenyl radical, or a radical of the formula R ⁷ -G-,

in the

R ⁷

represents hydrogen, a hydroxyl, carboxyl, epoxy or aldehyde group, (C ₁ -C ₄ ) alkyl, (C ₁ -C ₄ ) alkoxy
and

G

represents a divalent, optionally branched, C ₂ - to C ₆₀ -hydrocarbon residue which can be interrupted by non-adjacent ether, ester, amide, carbonate or urethane groups and which is optionally substituted by hydroxyl groups or alkyl or aryl residues, stands

or A for a radical of the formula

stands in the

R ¹ , R ² and R ³

independently of one another represent hydrogen or a monovalent C ₂ -C ₆₀ -hydrocarbon radical which optionally contains one or more non-adjacent ether, imino, amide, urea, urethane, ester or carboxyl groups and which optionally has one or 2 carboxyl groups -COOM and / or 1 or 2 hydroxyl groups is substituted,

in which

M

for hydrogen or Na ⁺ , K ⁺ , Li ⁺ , NH ₄ ⁺ ,

stands,
wherein R ⁴ , R ⁵ and R ⁶ independently of one another are C ₁ -C ₁₈ alkyl, in particular C ₁ -C ₄ alkyl or substituted C ₁ -C ₁₈ alkyl, in particular hydroxyalkyl, or aralkyl, in particular benzyl,
and wherein R ¹ to R ³ are linked independently of one another via a single bond, a group -COO-, -CO- or -CONH- with the nitrogen atom, and
where R ¹ and R ^{2 are} not simultaneously linked to the nitrogen atom via a carbonyl group,

D and E

independently of one another represent a divalent C ₂ -C ₂₀ hydrocarbon radical which can be substituted by hydroxyl or interrupted by non-adjacent O atoms,

q

represents 0 to 3,

with the proviso that at least one end group of the formula (3a) is present in the event that the polysiloxane chain contains only structural units of the formula (2).

A

für einen carboxylgruppen-haltigen Rest der Formel

steht, in der

R¹, R² und R³

unabhängig voneinander für Wasserstoff oder für einen einwertigen C₂-C₆₀-Kohlenwasserstoffrest stehen, der gegebenenfalls eine oder mehrere nicht benachbarte Ether-, Imino-, Amid-, Harnstoff-, Urethan-, Ester- oder Carboxylgruppen enthält und der gegebenenfalls mit einer oder 2 Carboxylgruppen -COOM und/oder 1 oder 2 Hydroxylgruppen substituiert ist, und

wobei der Rest A mindestens mit einer Gruppe COOM substituiert ist
wobei

M

für Wasserstoff oder Na⁺, K⁺, Li⁺, NH₄ ⁺,

steht,
wobei R⁴, R⁵ und R⁶ unabhängig voneinander für C₁-C₁₈-Alkyl, insbesondere C₁-C₄-Alkyl oder substituiertes C₁-C₁₈-Alkyl, insbesondere Hydroxyalkyl, oder Aralkyl, insbesondere Benzyl, stehen,
und wobei R¹ bis R³ unabhängig voneinander über eine Einfachbindung, eine Gruppe -COO-, -CO- oder -CONH- mit dem Stickstoffatom verknüpft sind, und
wobei R¹ und R² nicht gleichzeitig für H stehen und auch nicht gleichzeitig über eine Carbonylgruppe mit dem Stickstoffatom verknüpft sind,

D und E

unabhängig voneinander für einen zweiwertigen C₂-C₂₀-Kohlenwasserstoffrest stehen, der durch Hydroxyl substituiert oder durch nicht benachbarte O-Atome unterbrochen sein kann,

q

für 0 bis 3 steht

R

für einen C₁ bis C₁₂-Alkylrest, einen C₁ bis C₁₂-Alkoxylrest, einen Hydroxylrest oder einen Phenylrest steht,

a

für 0 oder 1 steht,

k

für 0 bis 50 steht,

c

für 1 oder 2 steht, und

n

für 10 bis 1000 steht,

mit der Maßgabe, dass mindestens eine Endgruppe der Formel (3a) vorhanden ist für den Fall, dass die Polysiloxankette nur Struktureinheiten der Formel (2) enthält.

Carboxyl-containing polysiloxanes are particularly preferred, characterized in that
that the polysiloxane chain has at least one structural unit of the formula (1) [AR _a SiO _{(3-a) / 2} ] _k and / or at least one structural unit of the formula (2) [R _c SiO ( _{4-c) / 2} ] _n and optionally one or more end groups selected from the formulas R ₃ SiO _1/2 and AR ₂ SiO _1/2 contains, where

A

for a carboxyl group-containing radical of the formula

stands in the

R ¹ , R ² and R ³

independently of one another represent hydrogen or a monovalent C ₂ -C ₆₀ -hydrocarbon radical which optionally contains one or more non-adjacent ether, imino, amide, urea, urethane, ester or carboxyl groups and which optionally has one or 2 carboxyl groups -COOM and / or 1 or 2 hydroxyl groups is substituted, and

wherein the radical A is substituted with at least one group COOM
in which

M

for hydrogen or Na ⁺ , K ⁺ , Li ⁺ , NH ₄ ⁺ ,

stands,
wherein R ⁴ , R ⁵ and R ⁶ independently of one another are C ₁ -C ₁₈ alkyl, in particular C ₁ -C ₄ alkyl or substituted C ₁ -C ₁₈ alkyl, in particular hydroxyalkyl, or aralkyl, in particular benzyl,
and wherein R ¹ to R ³ are linked independently of one another via a single bond, a group -COO-, -CO- or -CONH- with the nitrogen atom, and
where R ¹ and R ^{2 are} not simultaneously H and are not simultaneously linked to the nitrogen atom via a carbonyl group,

D and E

independently of one another represent a divalent C ₂ -C ₂₀ hydrocarbon radical which can be substituted by hydroxyl or interrupted by non-adjacent O atoms,

q

stands for 0 to 3

R

represents a C ₁ to C ₁₂ alkyl radical, a C ₁ to C ₁₂ alkoxyl radical, a hydroxyl radical or a phenyl radical,

a

represents 0 or 1,

k

represents 0 to 50,

c

represents 1 or 2, and

n

stands for 10 to 1000,

with the proviso that at least one end group of the formula (3a) is present in the event that the polysiloxane chain contains only structural units of the formula (2).

Suitable polysiloxanes are preferably polydialkylpolysiloxanes, polyalkylarylpolysiloxanes, with hydroxyalkyl, aminoalkyl, carboxyalkyl, hydroxyaryl, Carboxyaryl groups substituted polysiloxanes, which have a spacer with the polysiloxane main chain are connected, the spacer itself being an alkylene radical or a by functional groups, e.g. Ester, amide, urethane, carbonate, urea, ether, Imino, interrupted hydrocarbon residue can be.

The carboxyl group-containing compounds listed in EP-A 11 08 765 are particularly preferred Polysiloxanes and the polysiloxane raw materials used to manufacture them. Also preferred are those polysiloxanes that have hydrolyzable Residues have (Si-OR groups), which cross-link the Lead polysiloxane.

Polysiloxanes which are present as an aqueous dispersion are particularly preferred can therefore be used in an aqueous liquor.

The hydrophobizing agent is preferred in an amount of 0.1 to 10% by weight, based on fold weight, but especially 1 to 5% by weight. Using of water repellents without ionic, pH-sensitive groups is the Amount preferably 0.1 to 9 wt .-%. In the latter case, preferably Emulsifier with ionic, pH-sensitive groups in an amount of 5 to 25 wt .-%, based on the water repellant used.

The self-emulsifying water repellent with ionic, pH-sensitive groups is preferably in an amount of 0.1 to 10 wt .-%, but especially 1 to 5% by weight based on the shaved weight.

The chrome-free leather, which may be retanned with the water repellent is preferably tanned with iron compounds Service.

To do this, you generally use the preferably picked nakedness and treats the nakedness with an iron salt. The iron salt can either be of the nakedness Salt or as an aqueous solution. Preferred iron salts are those of iron in the +3 oxidation state, for example iron chloride, iron sulfate, basic iron sulfate as well as iron in the oxidation state +2 as Ferrous sulfate. Based on the nakedness used, the amount of iron is preferably from 0.3 to 5% by weight, in particular 1 to 3% by weight.

The tanning is preferably done in water at a temperature of 0 - 60 ° C, preferably 20-37 ° C.

After adding the iron salts for tanning, the tanning liquor should have a pH of 1.0 to 3.2, preferably from 1.4 to 2.5. After a reasonable time to Penetration of 30 min. up to 24 h, preferably 1 h to 12 h, the pH of the tanning liquor raised to fix the iron salts. For this purpose, a basic one is preferably used Connection, e.g. B. sodium hydroxide, carbonate, bicarbonate, formate, calcium carbonate or magnesium oxide is used. A pH range from 3.0 to 6.0, preferred 3.1 to 4.0 should be achieved.

The iron-tanned leather thus obtained has a shrinking temperature of greater than 70 ° C, preferably greater than 75 ° C. It also has a uniform one Yellow color. For example, it can be mechanically aftertreated by wilting, folding, etc. on conventional tanneries.

Then the tanned in this way and optionally mechanically post-treated Leather can be retanned in an optional step.

In the context of this application, "retanning" means post-treatment from chrome-free tanned leather to color, levelness, softness, fullness but especially to optimize the behavior against water (hydrophobicity) and Fix tannins and auxiliaries.

During retanning, the pH is generally in the range from 4.1 to 8.0 and is therefore suitable for penetration of the retanning products into the Leather. To any retanning agents used as well as those with pH-sensitive Fixing group-provided hydrophobizing agents or emulsifiers becomes the pH after the hydrophobization, preferably to 2.5 to 4.0, in particular to 3.3 lowered to 3.9. Organic acids such as formic acid, Acetic acid or oxalic acid, optionally in combination with inorganic acids such as sulfuric acid or phosphoric acid.

In preparation for the retanning process, the water content of the iron-tanned Leather preferably reduced by withering, and then the thickness of the leather corrected by folding if necessary.

The retanning process is preferably carried out in a tanning drum in an aqueous liquor a temperature of 0 to 70 ° C, especially from 20 to 50 ° C instead and includes optionally, other than the hydrophobicizing and lubricating agents according to the invention Tools such as Polymers, synthetic retanning agents, vegetable retanning agents, Colorants, acids and bases.

The synthetic tanning agents suitable for this application are e.g. B. water-soluble condensation products from sulfonated aromatics, formaldehyde and optionally further substances from the groups of aromatics, urea, or urea derivatives.

Vegetable tannins are tannins obtained from vegetable sources from the Classes of condensed tannins or hydrolyzable tannins e.g. Chestnut extract, Mimosa, Tara or Quebracho.

The dyes are common water-soluble in leather applications Dyes, e.g. from the groups of acid dyes, direct dyes, Metal complex dyes or substantive dyes.

The preferred polymers for use are high molecular weight water soluble or water dispersible products e.g. from the (Co) polymerization reaction of unsaturated acids and their derivatives with e.g. filling or greasing effect on leather.

Acids and bases are used to change the pH of the aqueous liquor to influence the penetration properties of the compounds used or to fix them.

The hydrophobizing and fatliquoring agents according to the invention are used in Generally in 20 to 1000, preferably 50 to 200% aqueous liquor, based on Weight of the leather used, in a pH range from 4.1 to 8.0, preferably 5.0 applied to 7.5. The addition of 0.1 to 10% by weight, preferably 1-5% by weight of the Hydrophobing agents and 1 - 20%, preferably 2 - 12% of the fatliquor can in one or more steps. Other tools used can also be added in one or more steps together with or separately from the products according to the invention.

The retanning process is carried out in 1 - 48 h, preferably in 1.5 - 24 h, especially in 2 - 8 h.

The process of a retanning process is to be illustrated by the examples but by no means limited to this.

The wet leather obtained from retanning can be processed using the usual technical methods Methods and machines are dried and finished, e.g. through vacuum drying, stenter drying or hanging drying and optional Subsequent tunneling, milling, grinding or polishing.

The leather obtained can improve the surface properties and physical fastness with commercially available products and machines with a polymeric film layer, such as e.g. described by W. Wenzel in Aqueous Finishing of Leather, JALCA, 1991, 442-455.

The preferably used pickled pelts for iron tanning are preferred acid pretreated, especially at pH 2-5, especially preferred at 3-4. This acid pretreatment is preferably decalcified and pickled nakedness used.

Compounds such as carboxylic acids are particularly used for pimples such as formic acid, acetic acid or oxalic acid or inorganic acids such as Sulfuric acid or acidic salts of sulfuric acid or mixtures thereof.

It has been found that the addition of di- or polyfunctional carboxylic acids, for example polymeric or non-polymeric compounds in the acidic Pretreatment has a particularly positive effect on the properties of the leather.

Particularly preferred non-polymeric acids are difunctional carboxylic acids such as tartaric acid, maleic acid, glutaric acid, phthalic acid and / or adipic acid; trifunctional carboxylic acids such as citric acid. Preferred polymeric carboxylic acids are copolymers which can be obtained by radical polymerization using (meth) acrylic acid, maleic acid or itaconic acid, maleic anhydride or their derivatives with other comonomers which contain no carboxyl groups. Preferred copolymers are those which, by radical copolymerization of the above-mentioned monomers containing carboxyl groups, with at least one monomer from the group of vinyl compounds such as, for example, styrene, diisobutylene, ethylene, propylene, vinyl ether, vinyl ester, (meth) acrylic acid esters of alcohols with C ₁ to C ₃₀ - Hydrocarbon atoms etc. are produced (= short description for suitable polyacrylates). Terpolymers or copolymers which are composed of more than 3 comonomers are also suitable.

These acids are preferably obtained in an amount of 0.5 to 10% by weight used on the nakedness used, in particular 1-4 wt .-%.

The acidic pretreatment preferably proceeds in such a way that to the nakedness used Pimples are given in an amount so that the pH of the pickled bare on a value of 2-5, in particular reduced to 3-4. The pimple connections are preferably added to the nakedness in a tanning drum in aqueous solution. This is generally done at a temperature of 0 to 60 ° C, especially at 20 to 37 ° C. It is preferably 10 min. up to 24 h, especially 30 min. up to 2 h pretreated.

A fatty agent is particularly preferred for the acidic pretreatment added.

Preferred lubricants for this use are those that are free of electrolyte stable anionic emulsifiers, e.g. sulfonated, sulfated or sulfited compounds with an emulsifying effect. In question here z. B. Fats and oils based on long-chain alkanes, alcohols, esters or others hydrophobic hydrocarbons. These compounds can be natural or be of synthetic origin, such as, for example, fish oils, claw oils, vegetable oils or Mineral oils.

In a preferred application form, these fatliquoring agents can be emulsifiers based on carboxylic acids. Polycarboxylic acids or polyethers are added, to facilitate processing in an aqueous liquor.

The fatliquor used in the pretreatment can have the properties of affect the finished leather, especially in terms of softness and Water resistance. Based on the pelt weight, 0.1 - 5% by weight are particularly important preferably 0.5-3% by weight added.

Examples : example 1 Production of a silicone-based water repellent with an internal emulsifier (corresponds to SIL 4 from EP-A 11 08 765)

1400 g of trimethylsilyl-terminated polydimethylsiloxane (viscosity 5000 mm ² / s, 25 ° C.) (commercial product: BAYSILONE® Oil M 5000) are introduced. Then 49.5 g of 2-aminoethyl-3-aminopropyl-methyl-dimethoxysilane (Dynasilan® 1411, from Hüls) and then 0.86 g of sodium hydroxide solution (50% strength) are added. The contents of the kettle are heated to 115 ° C. in the course of 2 hours. The mixture is stirred at 115 ° C. for 5.25 hours, a gentle stream of N _{2 being} passed over. The mixture is then stirred under vacuum at 65 hPa for 0.75 hours. 1.5 g of distillate are removed during the condensation (6 hours). After the elimination of methanol has ended, the batch is cooled to 25 ° C. with stirring. A polysiloxane functionalized with 2-aminoethyl-3-aminopropyl side chains is obtained (base N content = 0.44% by weight, viscosity at 20 ° C./100 s ^-1 = 140 mPas).

300 g of the aminopolysiloxane thus produced with 0.44% by weight of base N content are introduced at 25 ° C. and 18.5 g of maleic anhydride are stirred in. The suspension obtained is heated to 65 ° C. and stirred at 65 ° C. for 1 hour. This creates a clear solution. The IR spectrum shows no anhydride band at 1850 cm ^-1 . The viscosity of the intermediate is approx. 30,000 mPas at 100s ^-1 and 20 ° C. The mixture is then cooled to 50-55 ° C. 10.6 g of triethylamine are metered in at 55 ° C. with vigorous stirring. The batch is stirred at 55 ° C. for a further 20 minutes, the viscosity gradually increasing (viscosity 20 ° C., D = 10 s ^-1 : approx. 50,000 mPas). Then 100 g of isopropanol are added and the mixture is stirred at 55 ° C. for 30 minutes. 550 g of water are pumped in at 50-55 ° C. with rapid stirring within 3 hours. The dispersion obtained is freed from the solvent at 55 ° C. and 140-250 hPa. 117.5 g of isopropanol-water mixture are distilled off. A white, finely divided emulsion is obtained. Under these conditions, no foam is observed during the distillation. Then it is cooled to room temperature (≤30 ° C) and filtered through a 20 µm sieve. Solids content 36.9% PH value approx. 7 (undiluted) average particle size 174 nm viscosity 36 mPas (at 100 sec ^-1 , 20 ° C).

Example 2 Production of a silicone-based waterproofing agent with an internal emulsifier and a little external emulsifier

654.4 g of trimethylsilyl-terminated polydimethylsiloxane (viscosity 1000 mm ² / s, 25 ° C.) (commercial product: BAYSILONE® Oil M 1000) are introduced. Then 29.3 g of 2-aminoethyl-3-aminopropyl-methyl-dimethoxysilane (Dynasilan® 1411, from Hüls) and then 0.4 g of sodium hydroxide solution (50% strength), optionally diluted with 5 g of water, are added. The contents of the kettle are heated to 115 ° C. in the course of 2 hours. The mixture is stirred at 115 ° C. for 6 hours, a gentle stream of N _{2 being} passed over. The mixture is then stirred under vacuum at 65 hPa for 1 hour. 9.5 g of distillate are removed during the condensation (6 hours). A polysiloxane functionalized with 2-aminoethyl-3-aminopropyl side chains is obtained (base N content = 0.56% by weight, viscosity at 20 ° C./100 s ^-1 = 104 mPas).

The aminopolysiloxane thus produced is initially charged at 55 ° C. and 15.6 g of caprolactone and 130 g of ethyl acetate are added. Then 0.2 g of titanium tetrabutylate or dibutyltin dilaurate and 10 g of ethyl acetate are added. The mixture is stirred for 10 hours at about 75 ° C. (The carbonyl band of the lactone (no longer present at 1722 cm ^-1 ) is in the IR spectrum. Then the ethyl acetate is distilled off (about 140 g). After cooling At 50 ° C., 170 g of acetone and 26.9 g of succinic anhydride) are added and the mixture is stirred at 65 ° C. for 2 hours (anhydride is no longer detectable). Then 29.4 g of triethylamine are metered in with stirring and the mixture is stirred for a further 10 minutes. Then 340 g of ethanol are added. 1200 g of water are pumped in at 55 ° C. with rapid stirring within 3 hours. After adding 0.4 g of Respumit S in 40 g of water, 20 g of a cyanamide-polyurea adduct, hereinafter referred to as C-PUR, are added as an emulsifier. The dispersion obtained is freed from the solvent (520 g of distillate) at 50 ° C. and 140-250 hPa and filtered through a 20 μm sieve. A white, finely divided emulsion is obtained.

If necessary, aftertreatment during the emulsification process or afterwards by means of a jet disperser (nozzle principle), a flow cell with ultrasound sonotrode or by means of a high shear mixer (rotor-stator principle) or by using a high-pressure homogenizer to adjust the particle size of the emulsion. Solids content 37% by weight PH value 7.5 (undiluted) average particle size 300 nm viscosity 25 mPas (at 100 sec ^-1 , 20 ° C) storage stability very good

Description of the preparation of the cyanamide-polyurea adduct, C-PUR, for example 2

2240 g of a difunctional hexanediol polycarbonate diol (OH number = 56), 82 g of a difunctional propylene oxide polyether (OH number = 56) are dewatered at 120 ° C / 15 hPa. At 80 ° C, 363 g of 3,5-bis (6-isocyanatohexyl) -2,4,6-trioxo-tetrahydro-1,3,5-oxadiazine (technical product, MW = 422.0), 67, 2 g of hexa-methylene diisocyanate and 184.3 g of isophorone diisocyanate were added. After 3 hours at 90 ° C the prepolymer is diluted with 6000 g acetone. 18.0 g of ethylenediamine and 12.5 g of hydrazine hydrate in 300 g of water are added to this solution and the mixture is stirred at 50 ° C. for 15 minutes. A solution of 33.6 g of cyanamide in 400 g of water is then added. Another 20 minutes later, 80.7 g of triethylamine are added. The CO ₂ evolution is ended after 45 minutes. The mixture is diluted with 6000 g of water and then the acetone is distilled off under reduced pressure. The result is a finely divided dispersion with an average particle size of the disperse phase of approx. 95 nm, a solids content of 32.5% and an outlet viscosity of 12 seconds.

The composition of suitable cyanamide polyadducts is like that The following example shows, not to the already mentioned composition of C-PUR limited. A cyanamide polyaddition product in which analogous to C-PUR, the input materials and quantities were varied:

To a dehydrated polyol mixture from 157.1 g of a difunctional hexanediol polycarbonate diol (OH number = 56), 51.9 g of a difunctional one on bisphenol A. started propylene oxide polyether (OH number = 56), 0.86 g of 2-ethylhexanol at 60 ° C 32.5 g of 3,5-bis (6-isocyanatohexyl) -2,4,6-trioxo-tetrahydro-1,3,5-oxadiazine (technical product, MW = 422.0), 11.3 g hexa-methylene diisocyanate and 29.7 g Isophorone diisocyanate added.

After 3 hours at 90-95 ° C the prepolymer is diluted with 663 g acetone. After an NCO content of 1.1% has been reached, a solution of 1.43 g of hydrazine hydrate and 5.69 g of isophoronediamine in 42.1 g of water is added at 50-55 ° C. and the mixture is stirred at 50 ° C. for 15 minutes. Then 36.6 g of a 10% aqueous solution of cyanamide are added. Another 10 minutes later, 8.7 g of triethylamine are added. The CO ₂ evolution is ended after 1 hour. The mixture is diluted with 632 g of water and then the acetone is distilled off under reduced pressure. The result is a finely divided dispersion with an average particle size of the disperse phase of approx. 70 nm, a solids content of 30% and a viscosity of approx. 10 mPas at 20 ° C./10 s ^-1 .

Example 3 Production of a silicone-based water repellent (non-anionic) with external emulsifier

100 g of a linear dimethylpolysiloxane with pendant 2-aminoethylaminopropyl substituents and trimethylsilyl end group and / or dimethylsilyl methoxy end group, characterized by a base nitrogen content of 0.20% and a viscosity of 650-700 mPas at 20 ° C, with at 20 ° C 15.4 g of an emulsifier, e.g. Emulsifier ASN (25% in water) from Bayer AG, 12.8 g of cyclohexanol or isobutanol and 0.3 g of acetic acid are stirred. Then be 180 g of water are metered in within 30 minutes.

Konzentration: 35%

pH-Wert: 6,9

Teilchengröße: < 100 nm

Viskosität: < 50 mPas

A transparent emulsion is obtained

Concentration: 35%

pH: 6.9

Particle size: <100 nm

Viscosity: <50 mPas

Example 4 Lubricant based on solvents

400 g of a mixture of claw oil and vegetable oil in a ratio of 2: 1 is in 500 g Dissolved isopropanol. 30 g of PVA 40/98 and 70 g of an ethoxylated solution are used for the solution Given fatty acid.

Stirring in water gives a stable emulsion of the fatliquor.

Example 5 Lubricant based on a mineral oil

A mixture of 300 g mineral oil, viscosity 100 mPas, 80 g of a neutralized Acrylic acid / stearyl methacrylate copolymer and 620 g of water are mixed using a Dissolver blended. High pressure dispersion at 700 bar makes it stable Emulsion with particle size <200 nm generated.

Example 6 Fat oil based on fish oil

Purified fish oil and water are mixed in a ratio of 1: 3 using a jet disperser processed into an emulsion with particle size <100 nm. The emulsion will by adding 10% acrylic acid / methacrylic acid / ethylhexyl methacrylate copolymer and 2% PVA 26/88 stabilized.

Example 7

Tanning process A, tanning with iron salts using a fatliquor. Base product split cowhide, 3.0 mm. All quantities refer to the weight of the sheer. % product ° C Time min comment do the washing up water 35 deliming 100 water 35 2.0 ammonium sulfate 0.3 sodium bisulfite 10 stain 1.1 Protease 90 pH: 9.1 Fleet off do the washing up water 20 preparation 20 water 20 pimple 6.0 sodium chloride 5 ° Bé:> 6 0.3 Preservative (active ingredient CMK) 2.0 Fatliquor (Ex. 5) 5.0 mono-sodium phthalate 60 pH: 6.4 1.0 Formic acid 85% 1:10 15 1.5 Sulfuric acid 1:10 60 pH: 3.4 tanning 13.5 Basic iron (III) sulfate 45% 120 pH: 1.7;
penetration dull 100 water 2.0 sodium 30 pH: 2.3 0.7 magnesia 40 ° C 60 pH: 3.0 0.7 magnesia 45 ° C 60 pH: 4.2 do the washing up water Analytical data: Fe content 3.7%

Example 8

Tanning process B tanning with iron salts without using a fatliquor; Base product split cowhide, 4.5 mm. All quantities refer to the weight of the sheer. % product ° C Time min comment do the washing up water 35 deliming 100 water 35 2.5 ammonium sulfate 0.3 sodium bisulfite 10 stain 1.1 Protease 90 pH: 9.1 Fleet off do the washing up water 20 preparation 20 water 20 pimple 6.0 sodium chloride 5 ° Bé:> 6 0.3 Preservative (active ingredient CMK) 3.0 Methacrylic acid copolymer 1.0 glutaric 60 pH: 4.4 1.0 Formic acid 85% 1:10 15 0.5 sulfuric acid 60 pH: 3.4 tanning 6 Iron (III) sulfate 120 pH: 1.7;
penetration dull 100 water 1.1 Soda 1:10 30 pH: 2.0 1.1 Soda 1:10 30 pH: 2.7 1.1 Soda 1:10 30 pH: 3.3 do the washing up water Analytical data: Fe content 3.6%

Example 9

Retanning process A, production of a watertight saddle leather, thickness 3.5-4 mm, starting from example 7; all quantities used relate to rebate weight. process + % product ° C Time min comment To wash 200 water 35 15 Fleet off Neutralization 100 water 35 2.0 sodium 4.5 sodium bicarbonate 60 pH 3.0 Lubricant Ex 5 ü.N. pH 5.0 Fleet off To wash 100 water 35 Fleet off retanning 50 water 35 0.3 ammonium bicarbonate 15 pH 6.0 4.0 Lubricant Ex 5 4.0 Polymeric retanning agent, polyaspartic acid derivative 30 8.0 Synthetic tanning agent, phenolsulfonic acid condensate 4.0 resin tanning 60 3.0 Chestnut unsweetened 2.0 Black dye 90 50 water 50 5 1.0 Formic acid 1:10 30 pH 4.3 Fleet off 200 water 30 5 Fleet off 50 water 30 1.8 ammonium bicarbonate 30 pH 7.0 4.0 Water repellant Ex 2 60 pH 7.0 1.0 Formic acid 1:10 15 1.0 Formic acid 1:10 15 1.0 Formic acid 1:10 15 1.0 Formic acid 1:10 60 pH 3.5 do the washing up water 50 5 do the washing up water 20 5

Wasserdichtigkeit: Wasserdurchtritt gemessen nach DIN 53338: > 8 h bei 9 % Wasseraufnahme.

Analytische Daten: Fe-Gehalt 2.1 %, Si-Gehalt 0.7 %

Vacuum drying (60 ° C, 3 min), air conditioning (65% humidity), studs, ironing result in a very firm, full, deep black leather

Water resistance: water penetration measured according to DIN 53338:> 8 h with 9% water absorption.

Analytical data: Fe content 2.1%, Si content 0.7%

Example 10

Retanning process B, production of a shoe upper leather thickness 1.6-1.8 mm based on tanning process A; all quantities used relate to rebate weight. process + % product ° C Time min comment To wash 200 water 35 15 Fleet off Neutralization 100 water 35 3.0 Neutralization tanning agent, ditolyl ether sulfonic acid condensate 1.0 sodium 60 pH 5.8 4.0 Polymeric retanning agent, polyaspartic acid derivative ü.N. pH 5.8 Fleet off To wash 100 water 35 Fleet off retanning 50 water 35 4.0 Fatliquor Ex 6 2.0 Hydrophobing agent Ex. 1 4.0 Polymeric retanning agent, polyaspartic acid derivative 30 pH 6.0 4.0 Synthetic tanning agent, phenolsulfonic acid condensate 4.0 resin tanning 60 2.0 Dye brown 90 50 water 50 5 1.0 Formic acid 1:10 30 pH 4.1 Fleet off 200 water 30 5 Fleet off? 50 water 30 1.8 ammonium bicarbonate 60 pH 7.2 3.0 Hydrophobing agent Ex. 1 60 pH 7.1 1.0 Formic acid 1:10 15 1.0 Formic acid 1:10 15 1.0 Formic acid 1:10 15 1.0 Formic acid 1:10 60 pH 3.6 do the washing up water 50 5 do the washing up water 20 5

Wasserdichtigkeit: Wasserdurchtritt gemessen nach DIN 53338: > 8 h bei 12 % Wasseraufnahme.

Analytische Daten: Fe-Gehalt 3.3 %, Si-Gehalt 1.2 %

Vacuum drying (60 ° C, 2 min), air conditioning (65% humidity), cleats result in a soft, full, no matter dyed leather.

Water resistance: water penetration measured according to DIN 53338:> 8 h with 12% water absorption.

Analytical data: Fe content 3.3%, Si content 1.2%

Wasserdichtigkeit: Wasserdurchtritt gemessen nach DIN 53338: > 8 h bei 14 % Wasseraufnahme.

Wasserdampfdurchlässigkeit: 11 mg/cm² h

Analytische Daten: Fe-Gehalt 3.3 %, Si-Gehalt 1.1 %

The full-grain leather obtained was sanded to nubuck in two passes (paper grain size 120):

Water resistance: water penetration measured according to DIN 53338:> 8 h with 14% water absorption.

Water vapor permeability: 11 mg / cm ² h

Analytical data: Fe content 3.3%, Si content 1.1%

Example 11

Retanning process B, production of a split shoe upper leather thickness 1.3 - 1.5 mm based on tanning analogous to tanning process A; all quantities used relate to rebate weight. process + % product ° C Time min comment To wash 200 water 35 15 Fleet off Neutralization 50 water 40 4.0 Synthetic tanning agent, phenolsulfonic acid condensate 30 4.0 Polymeric retanning agent, methacrylic acid copolymer 30 1.0 sodium 3.0 Natrimbicarbonat 60 pH 5.6 3.0 Lubricant Ex 5 60 pH 5.6 Fleet off To wash 200 water 40 5 Fleet off retanning 100 water 40 3.0 Lubricant Ex 5 40 6.0 Synthetic tanning agent, diphenyl sulfone condensate 20 4.0 Polymeric retanning agent, polyaspartic acid derivative 40 pH 6.0 1.0 Pigment white 200 water 30 5 Fleet off? 50 water 30 1.8 sodium 45 pH 6.9 2.0 Lubricant Ex. 5 20 4.0 Water repellant Ex 2 45 pH 7.0 4.0 Synthetic tanning agent, diphenyl sulfone condensate with lignin sulfonate 30 1.2 Formic acid 1:10 30 1.2 Formic acid 1:10 15 1.2 Formic acid 1:10 30 pH 3.4 do the washing up water 50 5 do the washing up water 20 5

Tension drying, air conditioning (65% humidity), tunnels, millen, results in soft, round, light beige leather

Wasserdurchtritt gemessen nach DIN 53338: > 8 h bei 17 % Wasseraufnahme.

Wasserdurchtritt gemessen nach ASTM D2099-98: > 50000 Knickungen bei Wasseraufnahme 12 %

Wasserdampfdurchlässigkeit: 18 mg/cm² h

Analytische Daten: Fe-Gehalt 3.1 %, Si-Gehalt 1.0 %

Water resistance:

Water penetration measured according to DIN 53338:> 8 h with 17% water absorption.

Water penetration measured according to ASTM D2099-98:> 50000 kinks with water absorption 12%

Water vapor permeability: 18 mg / cm ² h

Analytical data: Fe content 3.1%, Si content 1.0%

Example 12

Retanning process B, production of a sheep's clothing leather 0.8 mm based on tanning analogous to tanning process A; all quantities used relate to rebate weight. process + % product ° C Time min comment Washing (2x) 300 water 40 pH 3.4 Fleet off Neutralization 150 water 40 2.0 Neutralization tanning agent, ditolyl ether sulfonic acid condensate 1.5 sodium bicarbonate 30 pH 6.0 3.0 Polymeric retanning agent, polyaspartic acid derivative 30 5.0 Fatliquor Ex 6 90 pH 5.5 over night Fleet off Washing (2x) 200 water 40 5 Fleet off retanning 150 water 40 2.0 synthetic tanning agent, phenolsulfonic acid condensate 10 1.0 Dye red 20 5.0 Polymeric retanning agent, polyaspartic acid derivative 30 5.0 Hydrophobing agent Ex. 3 60 3.0 resin tanning 1.0 Dye red 45 2.0 formic acid 30 pH 3.6 Fleet off 100 water 30 2.0 Ammonia 25% 1:10 40 pH 7.1 4.0 Hydrophobing agent Ex. 3 60 pH 7.0 1.3 Formic acid 1:10 15 1.3 Formic acid 1:10 15 1.3 Formic acid 1:10 60 pH 3.7 do the washing up water 50 5 do the washing up water 20 5

Wasserdichtigkeit:

Wasserdurchtritt gemessen nach DIN 53338: 185 min bei 14 % Wasseraufnahme. Wasserdampfdurchlässigkeit: 18 mg/cm² h

Analytische Daten: Fe-Gehalt 3.1 %, Si-Gehalt 1.0 %

Hanging drying, air conditioning (65% humidity), studs, millen, results in a soft, round, red leather.

Water resistance:

Water penetration measured according to DIN 53338: 185 min with 14% water absorption. Water vapor permeability: 18 mg / cm ² h

Analytical data: Fe content 3.1%, Si content 1.0%

Claims (12)

Chromium-free leather with a water resistance measured as penetration time according to DIN 53338 of at least 30 min. Chromium-free leather according to claim 1, characterized in that the penetration time according to DIN 53338 is at least 2 hours. Chromium-free leather according to at least one of the preceding claims, characterized in that it has an Fe content of 1 to 6% by weight, based on dry weight, determined after ashing. Chromium-free leather according to at least one of the preceding claims, characterized in that it has an Si content of at least 0.2% by weight, preferably at least 1.0% by weight, based on dry weight, determined as silicate after ashing. Chromium-free leather according to claim 3, characterized in that the leather contains a silicone, in particular silicone with a polysiloxane chain. Chromium-free leather according to at least one of the preceding claims, characterized in that the water vapor permeability measured according to DIN 53333 is greater than 0.8 mg / cm ² h, in particular greater than 2 mg / cm ² h. Use of silicones as a hydrophobizing agent for chrome-free tanned Leather. Use according to claim 7, characterized in that the silicone used is one which a) is self-emulsifying in water and has ionically pH-sensitive groups and / or b) is used in combination with an emulsifier, the emulsifier having ionic pH-sensitive groups. Process for the production of chrome-free leather according to claim 1, characterized in that chrome-free tanned leather is optionally retanned and treated by means of a hydrophobizing agent. A process for the production of chrome-free leathers according to claim 9, characterized in that an iron-tanned leather is optionally retanned and then treated by means of a hydrophobizing agent, in particular by means of a silicone. A method according to claim 10, characterized in that the bare to be tanned is acid pretreated before iron tanning, in particular with an organic di- or polycarboxylic acid. Use of leathers according to claim 1 as upholstery fabrics in the automotive industry, as upper leather in the shoe industry, as bag leather or as saddle leather.